


Kinktober 2019: Fontcest edition

by Tainted_Golden



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Alternate Universe - Underfell (Undertale), Alternate Universe - Underswap (Undertale), Anal Plug, Clothed Sex, Cock Rings, Come Inflation, First Time, Immobility, Inflation, Kinktober, Kinktober 2019, M/M, Swapfell Papyrus (Undertale), Swapfell Sans (Undertale), Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Papyrus (Undertale), Underswap Sans (Undertale)
Language: English
Status: In-Progress
Published: 2019-09-22
Updated: 2019-10-02
Packaged: 2020-10-25 23:29:31
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 2,681
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20732498
Author URL: https://archiveofourown.org/users/Tainted_Golden/pseuds/Tainted_Golden
Summary: So I've decided to participate in kinktober this year. It will be exclusively Fontcest, Sanscest and Papcest.Almost all the pairings are from Undertale, Underfell or Underswap.The first chapter is a list of the prompts for each day and the pairings for each day.The prompts are from Soft_Fluffle, and can be found here: https://archiveofourown.org/works/20492990





	1. Prompts List

**Author's Note:**

> I might change some things on here, but this is what I'm thinking so far.

Day 1: Inflation  
Pairing: Fell Papyrus/Swap Sans (Edgeberry)

Day 2: Hate fucking/angry sex  
Pairing: Fell Papyrus/Swap Papyrus (Spicyhoney)

Day 3: Public/semi-public sex  
Pairing: Classic Sans/Fell Sans (Kustard)

Day 4: Feed play/feederism  
Pairing: Swapcest

Day 5: Tentacles  
Pairing: Swap Sans/Nightmare Sans

Day 6: Roleplay  
Pairing: Fell Sans/Swap Sans (Cherryberry)

Day 7: Biting | Bloodplay | Heat cycle  
Pairing: Classic Papyrus/Fell Papyrus

Day 8: Begging  
Pairing: Classic Sans/Fell Papyrus

Day 9: Sensory depravation  
Pairing: Classic Sans/Fell Sans (Kustard)

Day 10: Mirrors  
Pairing: Fell Papyrus/Swap Sans (Edgeberry)

Day 11: Asphyxiation  
Pairing: Fontcest

Day 12: Bondage  
Pairing: Swapcest

Day 13: Vore | Fear  
Pairing: Fell Sans/Swap Papyrus (Honeymustard)

Day 14: Pet play  
Pairing: Swapfellcest

Day 15: Praise kink  
Pairing: Fell Sans/Swap Papyrus (Honeymustard)

Day 16: Humiliation  
Pairing: Fontcest

Day 17: Collars/leashes | Impact play  
Pairing: Classic Sans/Fell Papyrus

Day 18: Gun play  
Pairing: Fellcest

Day 19: Dubcon  
Pairing: Classic Papyrus/Fell Papyrus

Day 20: Facefucking/deepthroat  
Pairing: Classic Sans/Swap Papyrus

Day 21: Aggressive dominance  
Pairing: Fontcest

Day 22: Sub/dom  
Pairing: Fell Sans/Swap Papyrus (Honeymustard)

Day 23: Candle/Wax play  
Pairing: Classic Sans/Fell Sans (Kustard)

Day 24: Knife play  
Pairing: Fellcest

Day 25: Handjob  
Pairing: Classic Papyrus/Swap Papyrus

Day 26: Rape/noncon | Jealously/possessive  
Pairing: Fellcest, background Honeymustard

Day 27: Electricity  
Pairing: Fellcest

Day 28: Spit roasting  
Pairing: Fell Papyrus/Fell Sans/Swap Papyrus

Day 29: Stuck in a wall  
Pairing: Classic Sans/Fell Papyrus

Day 30: High school/college au  
Pairing: Fell Papyrus/Swap Sans (Edgeberry)

Day 31: Dehumanisation/objectification  
Pairing: Fellcest


	2. Day 1: Inflation

**Summary for the Chapter:**

> Pairing: Fell Papyrus/Swap Sans
> 
> Other tags that apply to this: First time, Clothed sex, anal plug

The Swap bro's house was unusually empty when Edge came through the front door. He'd only come by to ask about the meetup the brothers were planning. He had to make sure he was free, because his work with the royal guard came first.

Just as he was about to leave, Edge heard a loud moan from upstairs. Closing the front door quietly, he made his way up the stairs, stopping in from of Blues room. Another moan came through the door. Was Blue... Pleasuring himself?

Edge turned, disgusted, only for another wanton sound to stop him in his tracks. He should really leave, but the thought of Blue, sprawled out on his bed, eyes fluttering closed as he touched himself-

Well, Edge was going to hell anyway. He opened the door. The view was much how Edge had imagined it; Blue flushed and naked on his bed, eyes clothed. The one difference was the butt plug he was trying to fit in his hole to no avail.

"WELL." He said, announcing his presence. Blues' eyes snapped open, his face turning almost neon blue in embarrassment. "WHAT DO WE HAVE HERE? IT LOOKS LIKE YOU'RE NOT AS INNOCENT AS YOU MAKE YOURSELF OUT TO BE."

"I- UM." Blue struggled for something to say.

Edge walked in, magic already pooling to his pelvis. Blue shrunk away from him, closing his legs.

"DON'T HIDE FROM ME, BLUE." Edge purred. "IT LOOKS LIKE YOU COULD USE SOME HELP."

"W- WHAT?" Blue stuttered.

"I SAW YOU STRUGGLING TO GET THAT PLUG IN." Edge reached between Blues' legs, thumbing his penis with his leather-encased hands.

"EDGE." Blue said, distress clear in his voice.

"I CAN LEAVE IF YOU WANT." Edge said, removing his hand.

"N-NO I WANT-" Blue took a deep breath, "YOU REALLY WANT TO-?"

"IF YOU'LL LET ME."

"OK. YEAH, YES PLEASE." Edge grinned, pushing Blues' legs apart again. He pushed three of his fingers into Blues' mouth.

"SUCK." He instructed. Blue did as he was asked, his face morphing with concentration. Edge secretly loved the innocent, childish expressions of the other skeleton, especially in this situation.

He finally removed his fingers, and positioned the first one at Blues' entrance. "RELAX. BREATHE. IT'S NEVER GOING TO GO IN IF YOU'RE TENSING UP."

"OK." Blue did his best, shuddering out a few deeper breaths. Edge moved his other hand to wrap around the smaller skeletons' dick. The effect was immediate; Blue stopped thinking about Edge's fingers as soon as he touched him.

Edge worked Blue open slowly, savouring the sounds that escaped his mouth. He managed to fit three fingers inside him, fucking him on his hand. Satisfied, he removed them, and Blue whined at the loss. The smaller skeleton was barely coherent, shivering delicately, at Edge's mercy.

Edge unzipped his jeans, sighing in relief as the pressure was relieved from his dick. It was already slick with precum, and he kneeled on the bed, pulling Blues' legs apart so his knees rested on Edge's hips.

"EDGE?" Blue said, reaching down to grab his wrist. "I- I'VE NEVER- I MEAN, THIS IS-"

"IT'S OK, BLUE. DO YOU WANT ME TO STOP?"

"N- NO, I-"

"OK. JUST RELAX."

Edge waited for Blue to stop tensing up, before lining himself up and slowly pushing in. Blue was breathing harshly, gripping onto Edge's arm just a little too hard. Edge stopped, only the tip of his penis in.

"OK?" He asked, waiting until Blue nodded.

He continued slowly, stopping when he bottomed out. Blue was gasping, but he never asked for Edge to stop. Finally, after catching his breath, the smaller skeleton looked up at Edge, his eyelights glowing almost neon.

"Y- YOU CAN MOVE?" He said, sounding uncertain of himself. His eyes were searching for something in Edge's, looking worried.

"YOU SURE?" Edge said, unusually softly.

"YEAH."

Edge leaned forwards, putting a hand either side of Blues' head. He reached back to lift Blues' legs higher, so that he was gripping around Edge's waist. He started to move with slow, deliberate thrusts. Blue whimpered beneath him, his mouth open and eyelights looking almost molten.

"F- FASTER, GO FASTER."

Edge leaned down and pulled Blue into a kiss, his hips snapping roughly against Blues' thighs. He reached down with one hand and started jerking him off, catching his sinful moans by deepening the kiss.

The smaller skeleton was getting more desperate, and Edge increased the pace even more, Blue finally bucking up into Edge's thrusts as he came. Edge wasn't far behind him, watching in fascination as a stomach formed inside Blues' ribs to catch his cum. It bloated, rounding out as it filled with Edge's magic. He almost unconsciously pushed more magic into his dick, forcing himself to continue cumming until Blue was filled to nearly bursting.

Edge grabbed the discarded butt plug, tilting Blues' hips further up so as not to let even a drop escape. He pulled out, quickly plugging Blues' hole, trapping his cum inside. Though he'd never admit it, Blue looked incredible like this, filled up with Edge's magic, naked and spent.

"THERE. I TOLD YOU I'D HELP YOU GET THAT PLUG IN." Edge said, shaking off his weak, emotional thoughts.

"O- OH. RIGHT." Blue flushed even more, seemingly realising what had just happened. Edge pulled his pants back up, getting ready to leave. The almost betrayed look Blue gave him had him pausing. Fuck it.

"YOU KNOW. YOU LOOK IRRESISTIBLE LIKE THAT, FILLED UP WITH MY CUM." Blue looked away, somehow blushing more. He put a hand to his bloated stomach.

"REALLY?"

"I'M ALMOST TEMPTED TO TAKE THST PLUG BACK OUT AND STUFF YOU EVEN MORE. I WONDER IF I COULD MAKE YOUR STOMACH SO ROUND THAT YOU COULDN'T EVEN WALK." Blue looked at him with those big blue eyes, an almost hopeful look on his face.

"I- HAVE TO GO. DON'T TELL YOUR BROTHER THAT I WAS YOUR FIRST. HE'D KILL ME."

"RIGHT!" Blue smiled. "BUT- I'M KIND OF GLAD IT WAS YOU."

"I-" Edge could feel his face heating up. "I REALLY HAVE TO GO!" He left the room, blushing scarlet as he went back to the portal.

•••

Red was waiting for him when he got out of the shower.

"Sooooo, Blue huh?" He said, a shit eating grin on his face.

"SHUT UP SANS, OR I SWEAR I'LL LET THE DOGS EAT YOU."

"Ok, ok, chill Boss. Geez."


	3. Day 2: Hate Fucking/Angry Sex

**Summary for the Chapter:**

> Pairing: Fell Papyrus/Swap Papyrus
> 
> Other tags: Clothed Sex, Cock Rings, immobility

There was a knock at the door.

"COMING!" Blue yelled, taking off his oven gloves and almost running to the door.

Stretch was sitting on the sofa with Comic and Rus, the three of them turning as Blue opened the door.

Outside, Edge was standing scowling with Red nervously smiling behind him.

"HI EDGE! HI RED!"

"Hey Blue." Red made his best attempt at sounding at least somewhat friendly.

"LET'S GET THIS OVER WITH." Edge stormed into the house. He hated these monthly meetings the other two universes insisted on having. They originally wanted it to be weekly, and had the nerve to ask Edge to host one every third week. He had finally convinced them to only have one meeting a month, and had made it clear that he was not letting them come to his house. The only reason he showed up at all was because the others would pester him of he didn't.

"DINNER WILL BE READY IN ABOUT HALF AN HOUR. MAKE YOURSELVES AT HOME!" Blue said, his overly cheery voice already grating on Edge's nerves.

"Thanks Blue." Red said, moving to sit on the sofa. Edge followed him with a grumble.

"WHY ARE YOU BEING SO SOFT, 'RED'?" He asked, spitting out the nickname as if it offended him.

"I'm just being polite, Boss."

"YOU'RE BEING WEAK. ACTING LIKE THAT CAN ONLY GET YOU KILLED."

"Lighten up, dude. Your bro is acting a whole lot better than you are." Stretch butted in.

"Yeah. You're being kinda rude, y'know." Comic said, not even looking at him as he did.

"FINE. I'LL LET YOU CONTINUE THIS DISGUSTING FRATERNISING, BUT IT'S GOING TO END WITH YOU GETTING HURT." Edge took a seat next to Red, the smaller skeleton flinching. Nobody but Stretch seemed to have seen it.

Before Stretch could say anything, Blue was coming out of the kitchen, saying that the tacos were ready.

Stretch deliberately sat next to Edge, earning himself a slightly surprised glare. He always sat as far away from Edge as he could.

"WHAT ARE YOU DOING?" The skeleton in question growled.

"What, can't I try to get along with you?" That caught Blues' attention.

"YOU GUYS ARE TRYING TO WORK THINGS OUT? THAT'S GREAT!"

"Yeah, I figured we'd both spent long enough glaring from opposite ends of the table."

Soon enough, dinner was in full swing. Blue and Rus were talking loudly, Comic commenting sarcastically throughout. Red was watching, clearly amused by the conversation, but so far hadn't tried to join in. Edge was fuming silently the whole time.

"So." Stretch said, quiet enough that only edge would hear him, "I saw how much Red flinched when you say next to him." Edge turned towards him a fraction of a second too quickly, before composing himself.

"WHAT ARE YOU IMPLYING?" He growled, speaking lowly as well.

"I know that your world if pretty rough, but even so, Red shouldn't act like that around his brother."

"WHY WOULD YOU CARE? IT'S NONE OF YOUR BUSINESS."

"I care because he's a version of Blue. And if you're hurting him like I think you are, then you're more despicable than I thought."

Edge seemed genuinely surprised, then infuriated by that. "WHAT? NO- HOW DARE YOU? I'D NEVER HURT HIM."

"Ok. Thank the stars for small mercies, I guess."

"YOU REALLY HATE ME, DON'T YOU."

"Yeah. I'm not going to like, there's times I've really wanted to give you a taste of your own medicine."

"WHAT'S THAT SUPPOSED TO MEAN?"

"I've seriously considered tying you up and beating you, to show you how it feels for all the monsters you hurt."

"OH? I DIDN'T THINK YOU HAD IT IN YOU STRETCH." Whereas before he had only seemed annoyed, now there was a glint of something else in Edge's eye.

"Do you- you sick fuck. You like that?"

"YOU'RE THE ONE WHO SAID YOU WANTED TO DO IT." Stretch looked away, but he couldn't deny the way his face was heating up. "AND MAYBE WHILE WE'RE AT IT, I COULD PIN YOU UP AGAINST THE WALL AND FUCK YOU SO HARD YOU CAN'T WALK." Edge continued, lowering his voice further.

"Who's to say you'd be topping, asshole? There's no way I'd let someone like you fuck me."

"AS IF YOU'D BE STRONG ENOUGH TO TOP ME." Stretch stood up quite suddenly, drawing the attention of the rest of the table.

"Edge might have left something here, and I'm pretty sure I've seen it knocking about upstairs. Excuse me while we look for it." He gripped Edge's arm in his vice of a hand, practically dragging the other monster from his seat.

Stretch let go of Edge once he was standing, walking up the stairs and praying that Edge would follow him. He finally checked as he opened his door, to see Edge behind him, looking an odd mixture of amused and pissed off.

Stretch gestured through the door, watching impatiently as Edge casually sauntered through. Restraining himself from slamming the door, Stretch grabbed Edge by the wrists, pushing him into the wall. Before he could do more, Edge was pulling him forward into a heated kiss, raising his knee to grind it against Stretches crotch.

"You're fucking disgusting, you know that?" Stretch said as he pulled away. Edge only grinned.

"AND YOU'RE STUPID IF YOU STILL THINK YOU'RE FUCKING ME." Stretch growled, turning Edge's soul blue and flinging him across the room to land on the bed. Keeping him pinned in place, he knelt above him with a knee on his crotch in a mockery of their earlier position.

"Oh yeah?" Stretch undid Edge's belt, pulling his jeans down to expose his dick, not as long as Stretches but thicker and glowing a crimson red colour. Then he flipped Edge over, exposing his entrance.

"LET GO OF MY SOUL, ASSHOLE." Edge spat, still immobilised by Stretches magic.

"Nah. I like you better like this, unable to move, unable to hurt anybody."

"FUCK YOU."

"Actually, it's you who's gonna get fucked." Stretch reached for the lube he kept in his drawer, slicking up his fingers with it. He stuck his index finger is Edge's ass with no warning, making the other skeleton jump even immobilised as he was.

Stretch didn't take long to add another finger, pulling down his shorts and closing his fist around his dick.

"WHAT'S TAKING SO LONG?" Edge snapped, "ARE YOU REALLY LAZY WHEN IT COMES TO SEX TOO?"

"It almost sounds like you want me to fuck you, Edge."

"I WANT TO GET THIS OVER WITH, I'M GETTING BORED."

Stretch removed his fingers, lining himself up with Edge's entrance. He pushed in relentlessly, only stopping when his pelvis pressed up against Edge's magic. He started to move without giving the other skeleton time to adjust, setting a brutal pace, each thrust a little faster than the last. He grinned when Edge's mouth opened in a silent scream, eyelights blown wide with lust.

That was all it took for Stretch to cum, thrusting one last time and releasing his load deep into Edge's ass.

He got up, finally letting go of his hold on Edge's soul. Said skeleton was still hard, sitting up with a glare. Stretch smirked, digging through a drawer filled with various sex toys. Pulling out a cock ring, he grabbed Edge's soul again, ignoring his disgruntled "HEY!" and slipped the ring onto his dick, using a sneaky bit of magic he knew to make it impossible to remove for the next six hours. He wasn't sure if it worked cross universe, but it was worth a shot.

Finally letting Edge go for the last time, Stretch left the room.

"STRETCH, YOU ASSHOLE!" Edge yelled after him.

"Yeah, I hate you too." He responded mockingly.

"YOU'RE GOING TO LEAVE ME LIKE THIS?" He hissed.

"Yep, that's the plan." Edge made to retort, but Stretch had already shut the door, heading for the stairs.

Comic grinned at him from the sofa, and Stretch already regretted everything. It was gonna be a long night.


End file.
